crypto/authenc.c

   1 /*
   2  * Authenc: Simple AEAD wrapper for IPsec
   3  *
   4  * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  *
  11  */
  12
  13 #include <crypto/aead.h>
  14 #include <crypto/internal/hash.h>
  15 #include <crypto/internal/skcipher.h>
  16 #include <crypto/authenc.h>
  17 #include <crypto/scatterwalk.h>
  18 #include <linux/err.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/rtnetlink.h>
  23 #include <linux/slab.h>
  24 #include <linux/spinlock.h>
  25
  26 struct authenc_instance_ctx {
  27         struct crypto_spawn auth;
  28         struct crypto_skcipher_spawn enc;
  29 };
  30
  31 struct crypto_authenc_ctx {
  32         spinlock_t auth_lock;
  33         struct crypto_hash *auth;
  34         struct crypto_ablkcipher *enc;
  35 };
  36
  37 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  38                                  unsigned int keylen)
  39 {
  40         unsigned int authkeylen;
  41         unsigned int enckeylen;
  42         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  43         struct crypto_hash *auth = ctx->auth;
  44         struct crypto_ablkcipher *enc = ctx->enc;
  45         struct rtattr *rta = (void *)key;
  46         struct crypto_authenc_key_param *param;
  47         int err = -EINVAL;
  48
  49         if (!RTA_OK(rta, keylen))
  50                 goto badkey;
  51         if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
  52                 goto badkey;
  53         if (RTA_PAYLOAD(rta) < sizeof(*param))
  54                 goto badkey;
  55
  56         param = RTA_DATA(rta);
  57         enckeylen = be32_to_cpu(param->enckeylen);
  58
  59         key += RTA_ALIGN(rta->rta_len);
  60         keylen -= RTA_ALIGN(rta->rta_len);
  61
  62         if (keylen < enckeylen)
  63                 goto badkey;
  64
  65         authkeylen = keylen - enckeylen;
  66
  67         crypto_hash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  68         crypto_hash_set_flags(auth, crypto_aead_get_flags(authenc) &
  69                                     CRYPTO_TFM_REQ_MASK);
  70         err = crypto_hash_setkey(auth, key, authkeylen);
  71         crypto_aead_set_flags(authenc, crypto_hash_get_flags(auth) &
  72                                        CRYPTO_TFM_RES_MASK);
  73
  74         if (err)
  75                 goto out;
  76
  77         crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  78         crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
  79                                          CRYPTO_TFM_REQ_MASK);
  80         err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
  81         crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &
  82                                        CRYPTO_TFM_RES_MASK);
  83
  84 out:
  85         return err;
  86
  87 badkey:
  88         crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
  89         goto out;
  90 }
  91
  92 static void authenc_chain(struct scatterlist *head, struct scatterlist *sg,
  93                           int chain)
  94 {
  95         if (chain) {
  96                 head->length += sg->length;
  97                 sg = scatterwalk_sg_next(sg);
  98         }
  99
 100         if (sg)
 101                 scatterwalk_sg_chain(head, 2, sg);
 102         else
 103                 sg_mark_end(head);
 104 }
 105
 106 static u8 *crypto_authenc_hash(struct aead_request *req, unsigned int flags,
 107                                struct scatterlist *cipher,
 108                                unsigned int cryptlen)
 109 {
 110         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 111         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 112         struct crypto_hash *auth = ctx->auth;
 113         struct hash_desc desc = {
 114                 .tfm = auth,
 115                 .flags = aead_request_flags(req) & flags,
 116         };
 117         u8 *hash = aead_request_ctx(req);
 118         int err;
 119
 120         hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth),
 121                            crypto_hash_alignmask(auth) + 1);
 122
 123         spin_lock_bh(&ctx->auth_lock);
 124         err = crypto_hash_init(&desc);
 125         if (err)
 126                 goto auth_unlock;
 127
 128         err = crypto_hash_update(&desc, req->assoc, req->assoclen);
 129         if (err)
 130                 goto auth_unlock;
 131
 132         err = crypto_hash_update(&desc, cipher, cryptlen);
 133         if (err)
 134                 goto auth_unlock;
 135
 136         err = crypto_hash_final(&desc, hash);
 137 auth_unlock:
 138         spin_unlock_bh(&ctx->auth_lock);
 139
 140         if (err)
 141                 return ERR_PTR(err);
 142
 143         return hash;
 144 }
 145
 146 static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
 147                                  unsigned int flags)
 148 {
 149         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 150         struct scatterlist *dst = req->dst;
 151         struct scatterlist cipher[2];
 152         struct page *dstp;
 153         unsigned int ivsize = crypto_aead_ivsize(authenc);
 154         unsigned int cryptlen;
 155         u8 *vdst;
 156         u8 *hash;
 157
 158         dstp = sg_page(dst);
 159         vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;
 160
 161         if (ivsize) {
 162                 sg_init_table(cipher, 2);
 163                 sg_set_buf(cipher, iv, ivsize);
 164                 authenc_chain(cipher, dst, vdst == iv + ivsize);
 165                 dst = cipher;
 166         }
 167
 168         cryptlen = req->cryptlen + ivsize;
 169         hash = crypto_authenc_hash(req, flags, dst, cryptlen);
 170         if (IS_ERR(hash))
 171                 return PTR_ERR(hash);
 172
 173         scatterwalk_map_and_copy(hash, dst, cryptlen,
 174                                  crypto_aead_authsize(authenc), 1);
 175         return 0;
 176 }
 177
 178 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 179                                         int err)
 180 {
 181         struct aead_request *areq = req->data;
 182
 183         if (!err) {
 184                 struct crypto_aead *authenc = crypto_aead_reqtfm(areq);
 185                 struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 186                 struct ablkcipher_request *abreq = aead_request_ctx(areq);
 187                 u8 *iv = (u8 *)(abreq + 1) +
 188                          crypto_ablkcipher_reqsize(ctx->enc);
 189
 190                 err = crypto_authenc_genicv(areq, iv, 0);
 191         }
 192
 193         aead_request_complete(areq, err);
 194 }
 195
 196 static int crypto_authenc_encrypt(struct aead_request *req)
 197 {
 198         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 199         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 200         struct ablkcipher_request *abreq = aead_request_ctx(req);
 201         struct crypto_ablkcipher *enc = ctx->enc;
 202         struct scatterlist *dst = req->dst;
 203         unsigned int cryptlen = req->cryptlen;
 204         u8 *iv = (u8 *)(abreq + 1) + crypto_ablkcipher_reqsize(enc);
 205         int err;
 206
 207         ablkcipher_request_set_tfm(abreq, enc);
 208         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 209                                         crypto_authenc_encrypt_done, req);
 210         ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);
 211
 212         memcpy(iv, req->iv, crypto_aead_ivsize(authenc));
 213
 214         err = crypto_ablkcipher_encrypt(abreq);
 215         if (err)
 216                 return err;
 217
 218         return crypto_authenc_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 219 }
 220
 221 static void crypto_authenc_givencrypt_done(struct crypto_async_request *req,
 222                                            int err)
 223 {
 224         struct aead_request *areq = req->data;
 225
 226         if (!err) {
 227                 struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 228
 229                 err = crypto_authenc_genicv(areq, greq->giv, 0);
 230         }
 231
 232         aead_request_complete(areq, err);
 233 }
 234
 235 static int crypto_authenc_givencrypt(struct aead_givcrypt_request *req)
 236 {
 237         struct crypto_aead *authenc = aead_givcrypt_reqtfm(req);
 238         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 239         struct aead_request *areq = &req->areq;
 240         struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 241         u8 *iv = req->giv;
 242         int err;
 243
 244         skcipher_givcrypt_set_tfm(greq, ctx->enc);
 245         skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
 246                                        crypto_authenc_givencrypt_done, areq);
 247         skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
 248                                     areq->iv);
 249         skcipher_givcrypt_set_giv(greq, iv, req->seq);
 250
 251         err = crypto_skcipher_givencrypt(greq);
 252         if (err)
 253                 return err;
 254
 255         return crypto_authenc_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 256 }
 257
 258 static int crypto_authenc_verify(struct aead_request *req,
 259                                  struct scatterlist *cipher,
 260                                  unsigned int cryptlen)
 261 {
 262         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 263         u8 *ohash;
 264         u8 *ihash;
 265         unsigned int authsize;
 266
 267         ohash = crypto_authenc_hash(req, CRYPTO_TFM_REQ_MAY_SLEEP, cipher,
 268                                     cryptlen);
 269         if (IS_ERR(ohash))
 270                 return PTR_ERR(ohash);
 271
 272         authsize = crypto_aead_authsize(authenc);
 273         ihash = ohash + authsize;
 274         scatterwalk_map_and_copy(ihash, cipher, cryptlen, authsize, 0);
 275         return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;
 276 }
 277
 278 static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
 279                                   unsigned int cryptlen)
 280 {
 281         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 282         struct scatterlist *src = req->src;
 283         struct scatterlist cipher[2];
 284         struct page *srcp;
 285         unsigned int ivsize = crypto_aead_ivsize(authenc);
 286         u8 *vsrc;
 287
 288         srcp = sg_page(src);
 289         vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
 290
 291         if (ivsize) {
 292                 sg_init_table(cipher, 2);
 293                 sg_set_buf(cipher, iv, ivsize);
 294                 authenc_chain(cipher, src, vsrc == iv + ivsize);
 295                 src = cipher;
 296         }
 297
 298         return crypto_authenc_verify(req, src, cryptlen + ivsize);
 299 }
 300
 301 static int crypto_authenc_decrypt(struct aead_request *req)
 302 {
 303         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 304         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 305         struct ablkcipher_request *abreq = aead_request_ctx(req);
 306         unsigned int cryptlen = req->cryptlen;
 307         unsigned int authsize = crypto_aead_authsize(authenc);
 308         u8 *iv = req->iv;
 309         int err;
 310
 311         if (cryptlen < authsize)
 312                 return -EINVAL;
 313         cryptlen -= authsize;
 314
 315         err = crypto_authenc_iverify(req, iv, cryptlen);
 316         if (err)
 317                 return err;
 318
 319         ablkcipher_request_set_tfm(abreq, ctx->enc);
 320         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 321                                         req->base.complete, req->base.data);
 322         ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);
 323
 324         return crypto_ablkcipher_decrypt(abreq);
 325 }
 326
 327 static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 328 {
 329         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 330         struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
 331         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 332         struct crypto_hash *auth;
 333         struct crypto_ablkcipher *enc;
 334         int err;
 335
 336         auth = crypto_spawn_hash(&ictx->auth);
 337         if (IS_ERR(auth))
 338                 return PTR_ERR(auth);
 339
 340         enc = crypto_spawn_skcipher(&ictx->enc);
 341         err = PTR_ERR(enc);
 342         if (IS_ERR(enc))
 343                 goto err_free_hash;
 344
 345         ctx->auth = auth;
 346         ctx->enc = enc;
 347         tfm->crt_aead.reqsize = max_t(unsigned int,
 348                                       (crypto_hash_alignmask(auth) &
 349                                        ~(crypto_tfm_ctx_alignment() - 1)) +
 350                                       crypto_hash_digestsize(auth) * 2,
 351                                       sizeof(struct skcipher_givcrypt_request) +
 352                                       crypto_ablkcipher_reqsize(enc) +
 353                                       crypto_ablkcipher_ivsize(enc));
 354
 355         spin_lock_init(&ctx->auth_lock);
 356
 357         return 0;
 358
 359 err_free_hash:
 360         crypto_free_hash(auth);
 361         return err;
 362 }
 363
 364 static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
 365 {
 366         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 367
 368         crypto_free_hash(ctx->auth);
 369         crypto_free_ablkcipher(ctx->enc);
 370 }
 371
 372 static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 373 {
 374         struct crypto_attr_type *algt;
 375         struct crypto_instance *inst;
 376         struct crypto_alg *auth;
 377         struct crypto_alg *enc;
 378         struct authenc_instance_ctx *ctx;
 379         const char *enc_name;
 380         int err;
 381
 382         algt = crypto_get_attr_type(tb);
 383         err = PTR_ERR(algt);
 384         if (IS_ERR(algt))
 385                 return ERR_PTR(err);
 386
 387         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 388                 return ERR_PTR(-EINVAL);
 389
 390         auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 391                                CRYPTO_ALG_TYPE_HASH_MASK);
 392         if (IS_ERR(auth))
 393                 return ERR_PTR(PTR_ERR(auth));
 394
 395         enc_name = crypto_attr_alg_name(tb[2]);
 396         err = PTR_ERR(enc_name);
 397         if (IS_ERR(enc_name))
 398                 goto out_put_auth;
 399
 400         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 401         err = -ENOMEM;
 402         if (!inst)
 403                 goto out_put_auth;
 404
 405         ctx = crypto_instance_ctx(inst);
 406
 407         err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
 408         if (err)
 409                 goto err_free_inst;
 410
 411         crypto_set_skcipher_spawn(&ctx->enc, inst);
 412         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 413                                    crypto_requires_sync(algt->type,
 414                                                         algt->mask));
 415         if (err)
 416                 goto err_drop_auth;
 417
 418         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 419
 420         err = -ENAMETOOLONG;
 421         if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
 422                      "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
 423             CRYPTO_MAX_ALG_NAME)
 424                 goto err_drop_enc;
 425
 426         if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 427                      "authenc(%s,%s)", auth->cra_driver_name,
 428                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 429                 goto err_drop_enc;
 430
 431         inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
 432         inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
 433         inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
 434         inst->alg.cra_blocksize = enc->cra_blocksize;
 435         inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;
 436         inst->alg.cra_type = &crypto_aead_type;
 437
 438         inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
 439         inst->alg.cra_aead.maxauthsize = auth->cra_type == &crypto_hash_type ?
 440                                          auth->cra_hash.digestsize :
 441                                          auth->cra_type ?
 442                                          __crypto_shash_alg(auth)->digestsize :
 443                                          auth->cra_digest.dia_digestsize;
 444
 445         inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 446
 447         inst->alg.cra_init = crypto_authenc_init_tfm;
 448         inst->alg.cra_exit = crypto_authenc_exit_tfm;
 449
 450         inst->alg.cra_aead.setkey = crypto_authenc_setkey;
 451         inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
 452         inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
 453         inst->alg.cra_aead.givencrypt = crypto_authenc_givencrypt;
 454
 455 out:
 456         crypto_mod_put(auth);
 457         return inst;
 458
 459 err_drop_enc:
 460         crypto_drop_skcipher(&ctx->enc);
 461 err_drop_auth:
 462         crypto_drop_spawn(&ctx->auth);
 463 err_free_inst:
 464         kfree(inst);
 465 out_put_auth:
 466         inst = ERR_PTR(err);
 467         goto out;
 468 }
 469
 470 static void crypto_authenc_free(struct crypto_instance *inst)
 471 {
 472         struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
 473
 474         crypto_drop_skcipher(&ctx->enc);
 475         crypto_drop_spawn(&ctx->auth);
 476         kfree(inst);
 477 }
 478
 479 static struct crypto_template crypto_authenc_tmpl = {
 480         .name = "authenc",
 481         .alloc = crypto_authenc_alloc,
 482         .free = crypto_authenc_free,
 483         .module = THIS_MODULE,
 484 };
 485
 486 static int __init crypto_authenc_module_init(void)
 487 {
 488         return crypto_register_template(&crypto_authenc_tmpl);
 489 }
 490
 491 static void __exit crypto_authenc_module_exit(void)
 492 {
 493         crypto_unregister_template(&crypto_authenc_tmpl);
 494 }
 495
 496 module_init(crypto_authenc_module_init);
 497 module_exit(crypto_authenc_module_exit);
 498
 499 MODULE_LICENSE("GPL");
 500 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");